Whale song: why Maui's humpbacks sing

Only the males sing

Every singer ever recorded has been a male. He hangs nearly motionless, head down at 40 to 60 feet, flippers out, and sings for 10 to 20 minutes before surfacing to breathe, then goes down and sings the same song again, for hours. Some singers have been tracked through a whole night.

Singing peaks in the breeding season. It also happens on the migration route and, more quietly, in the feeding grounds. Whale Trust researchers on Maui have shown that a singing male often stops when another male approaches and the two may then swim off together, which does not look much like courtship.

It is actually a song

Roger Payne and Scott McVay published the first analysis in 1971 and showed that humpback sound was not random. It is built from units (a single moan or click), arranged into phrases, repeated into themes, sung in a fixed order to make a song that lasts between 5 and 30 minutes. Then the whale starts again from the top. The structure is as rigid as a verse-chorus form.

Everyone sings the same song, and it keeps changing

At any moment, every male in the North Pacific population is singing essentially the same song. Over a season it evolves, a phrase added here, a theme dropped there, and every male picks up the changes. Over a few years the song can turn over completely. Researchers have even traced songs spreading from one ocean population to another, east to west across the South Pacific, like a hit single, in what may be the largest example of cultural transmission in any non-human animal.

The 1970 album Songs of the Humpback Whale sold more than 100,000 copies, put the song on the Voyager spacecraft’s golden record, and did as much as any science to end commercial whaling.

How loud, how far

A humpback song is produced without exhaling, by moving air between internal sacs, and it is loud: up to about 170 decibels at the source, among the loudest sounds any animal makes. In the right conditions the low notes carry 10 to 20 miles underwater. Snorkelers off Kāʻanapali and Olowalu hear singers with no equipment at all; divers feel it in their chests.

What it is for

The candidates, none settled:

• Courtship: singing to attract females. The problem is that females rarely approach singers.
• Male-to-male signalling: advertising size and stamina to rivals, sorting out a hierarchy without fighting.
• Sonar: some researchers think the song may double as long-range echolocation to find other whales across the channel.
• All of the above, which is where most of the field currently sits.

How to hear it on Maui

Both operators on this guide carry hydrophones and play the song over the deck speakers on every trip. On the small raft you can sometimes hear it through the hull with the engines off. The sanctuary’s Hawaiian Islands Humpback Whale National Marine Sanctuary office in Kīhei streams a live hydrophone during the season. And if you snorkel from the beach at Kāʻanapali or Kapalua in February, hold still underwater and listen.